Recovery of virus from the blood of a vaccinee or seroconversion [ Time Frame: Throughout study ] [ Designated as safety issue: No ]

Immunogenicity of the LGT(TP21)/DEN4 vaccine against other TBE viruses [ Time Frame: Throughout study ] [ Designated as safety issue: No ]

Durability of antibody responses to Langat and other TBE viruses [ Time Frame: At Day 180 ] [ Designated as safety issue: No ]

Original Secondary Outcome Measures ICMJE (submitted: July 11, 2005)

Recovery of virus from the blood of a vaccinee or seroconversion

immunogenicity of the LGT(TP21)/DEN4 vaccine against other TBE viruses

durability of antibody responses to Langat and other TBE viruses at 6 months (180 days)

Current Other Outcome Measures ICMJE

Not Provided

Original Other Outcome Measures ICMJE

Not Provided

Descriptive Information

Brief Title ICMJE

Safety of and Immune Response to a Tick-Borne Encephalitis Vaccine (LGT(TP21)/DEN4) in Healthy Adults

Official Title ICMJE

Phase 1 Study of the Safety and Immunogenicity of Tick-Borne Langat/Dengue 4 Chimera (LGT(TP21)/DEN4), a Live Attenuated Vaccine for Tick-Borne Encephalitis

Brief Summary

Tick-borne encephalitis (TBE) is a viral illness common in the Northern Hemisphere, especially Europe and Asia. TBE infection may lead to central nervous system problems and death. The purpose of this study is to test the safety of and immune response to a TBE vaccine in healthy adults. The vaccine is related to a live attenuated virus developed against dengue virus infection.

Detailed Description

TBE is a common illness in Europe and Asia, where it is usually associated with mild illness but sometimes leads to long-term symptoms and even death. This study will evaluate the safety and immunogenicity of a live attenuated chimeric virus, LGT(TP21)/DEN4, which is derived from the Langat flavivirus and DEN4 dengue virus serotypes.

Each volunteer will be involved in the study for 180 days. Participants in Cohort 1 will be randomly assigned to receive LGT(TP21)/DEN4 or placebo at study entry. Cohort 2 will begin only after safety review of all participants in Cohort 1. Participants in Cohort 2 will receive a higher dose of LGT(TP21)/DEN4 or placebo.

After vaccination, participants will be asked to monitor their temperatures every day for 16 days and on Day 19. Study visits will occur every other day after vaccination until Day 16, followed by 5 additional visits at selected days through Day 180. Blood collection and a targeted physical exam will occur at each study visit. Some participants will be asked to undergo a skin biopsy or additional blood collection at selected visits.

One subcutaneous vaccination with a 10^3 PFU dose of LGT(TP21)/DEN4 vaccine given in the deltoid region of either arm. A second booster vaccination will be given 6 months after the first vaccination.

Intervention: Biological: LGT(TP21)/DEN4

Experimental: 2

One subcutaneous vaccination with a 10^5 PFU dose of LGT(TP21)/DEN4 vaccine given in the deltoid region of either arm. A second booster vaccination will be given 6 months after the first vaccination. This arm may enroll after Arm 1 depending on the immunological response of Arm 1.

Intervention: Biological: LGT(TP21)/DEN4

Placebo Comparator: 3

One subcutaneous vaccination with a placebo vaccine given in the deltoid region of either arm. A second placebo vaccination will be given 6 months after the first vaccination.